Manufacture of artificial silk



Patented Now 7, 1939 MANUFACTURE OF ARTIFICIAL SILK James J. Polak,Arnhem, and Johannes G. Weeldenburg, Ede, Netherlands, assignors toAmerican Enka Corporation, Enka, N. 0., a corpora tion of Delaware NoDrawing. Original application January 25, 1937, Serial No. 122,323.Divided and this application June 6, 1938, Serial No. 212,184. GermanyFebruary 15, 1935 Claims. (01. 18-54) This application is a division ofour application Serial Number 122,323, filed January 25, 1937 now PatentNo. 2,125,031, the latter being a continuation in part of ourapplication Serial No. 51,332, filed November 23, 1935. The presentinvention has to do with a new and novel method for use in themanufacture of yarn or other materials of artificial origin and theproducts thereof.

More specifically, the present invention concerns a novel prpcess formaintaining ideal'spinning conditions in the manufacture of yarn ofartificial origin.

In the manufacture of artificial filaments, threads, yarns, ribbons andthe like, a cellulosic solution is prepared and expressed or extrudedthrough minute openings into a coagulating or precipitating medium. Thismedium is usually either liquid or gaseous.

In preparing the cellulosic spinning solutions referred to in thespecific examples of the present case, cellulose is treated with causticto form alkali cellulose, which, with carbon disulphide, produces axanthate. This, in solution, produces a viscose spinning solution.

In the present specification we shall describe our invention withrespect to a viscose process, but it must be understood that theunderlying principle is broad, and that we do not wish to be limited toany specific, minute application of our concept.

In the commercial production of artificial yarn and analogous products,it is economically necessary, if possible, to provide for uninterruptedspinning of all filaments. Ordinarily the objections arising whichoccasion interruptions to the spinning or extruding step, are caused bythe contamination of the'spinnerets themselves. This fault can, webelieve, be traced to the presence of suspensions, reaction products,and impurities of various kinds in the viscose solution or the spinningbath which tend to agglomerate or deposit on the spinneret and partiallyor entirely block the small orifices therein. These materials mightinclude, among others, precipitated cellulose, sulphur deposits,particles of resin, secondary reaction products, and the like.

We have noted this phenomenon more especially when acid spinning bathsare employed and particularly where zinc sulphate is present in thebath. Sulphuric acid is the acid generally used in such spinning baths.

produces undesirable properties in the final product. Also, so-calledspinning hooks tend to form at the obstructions, either in or around theoridoes of the spinneret, which, when filaments are extrudedther'ethrough, might cause a temporary interruption of the spinning of afilament at the orifice affected, thus occasioning a tearing of thefilament. These faults incur additional expense more, spinnerets aremanufactured from precious.

and semi-precious stones, such as natural ruby, synthetic ruby, etcetera. Our improved procedures are applicable in the use of thesevarious types of spinnerets. The economic advantage of finding a simple,inexpensive method for keeping spinnerets operative during spinning istherefore apparent. "As will be subsequently pointed out, other improvedspinning conditions will be realized when following our procedureswherein we provide a solution for these problems in our presentinventive concept.

Briefly, we have discovered that if certain cation-active compounds areincluded either in the spinning bath and/or the spinning solution, theclogging of spinneret openings is considerably diminished orevenprevented, and a very remarkable improvement of the spinning processper se will result. More specifically, cationactive aliphatic,carbocyclic or heterocyclic substances have been employed with signalsuccess in actual practice. By stating that certain cationactivecompondsare employed it is intended to mean that only thosecation-active compounds are suitable which are sufiiciently soluble andsubstantially stable in the spinning bath or the cellulosic solution orin both. Cation-active compounds are surface-active compounds whichcarry in the cation the group or radical which is responsible for thesurface activity. In contradistinction anion-active compounds aresurfaceactive compounds which carry in the anion the group which isresponsible for the surface activity. Such groups responsible forsurface activity in this specification are called surfaceactive groups.Other groups or ions which are inert in this respect will be calledsurface-inactive or innocuous.

Surface activity as used herein is the property,

effected, which in itself represents an impurity,

other dissolved or suspended particles contaminating the spinning bathmay be also precipitated and removed.

Surface activity depends upon the presence of 5 one or more groups orradicals with long or extended chain-like structures which includeextended aliphatic, carbocyclic and 'heterocyclic chains or combinationsthereof. Compounds which contain a surface-active group show a tendency,according to the experiments and theory of Langmuir, to accumulate inthe surface or interface of the solution and to assume an orientedposition in which all of the extended chains lie parallel. Naturally,these substances 5 can show this property only in so far as they aredissolved. When the molecules ionize, the surface activity may beinduced by either the cationor the anion. This depends upon the positionof the extended chain when the molecule ionizes.

If, when the molecule ionizes, the extended chain remains with that partof the molecule bearing the positive charge, then it is said to becationactive; whereas, on the other hand, if the long chain remains withthat part of the molecule which bears a negative charge, it is said tobe anion-active. Most of the usual surface-active substances areanion-active, with which substances the present invention is notconcerned.

The compounds as exemplified below are illustrative of compounds whichmay be used in accordance with our invention. A general structuralformula for a compound of this type may be expressed as E A s.

XIEM c In this structure XI S- represents the cation and A representsthe anion. X represents a polyvalent atom, or a radical containing suchan atom, capable of being linked to a negative atom or radical and atthe same time to one or more other atoms or radicals. The letter 3indicates the valence of the atom or radical X. The invention alsocontemplates the presence of more than one atom symbolized by X in thecation. In this event one or more of the X atoms may be linked tosurface-active groups and to surface-inactive atoms or radicals asdescribed herein. S designates the radical or radicals inducingcation-activity, which are linked directly to the polyvalent atom of X.S may include one or more of the same or different aliphatic,carbocyclic and heterocyclic radicals and the letter m is a positivewhole number indicating the total number of such radicals. The radicalor radicals S should be such that when linked to X it or they willprovide, in an ionizing solvent, a surface-active cation. B. may behydrogen and/or one or more of the same or diiferent alicals which aredistinguished from those of B in that they do not inducesurface-activity into the cation. The letter 11. is a positive-wholenumber or zero and indicates the total number of such radicals and/orhydrogen atoms. This letter 11. also indicates the number of valences ofthe atom of X which remain available to be saturated by inactive atoms'or radicals of the cation.

The letter A represents an innocuous anion, i. e., an anion having nosurface-activity or at least less surface activity than the cation. Thisanion is linked directly to the polyvalent atom of X and may be an atomor an inorganic or organic radical. The letter 0 is a whole numberindicating the valence of the anion. The letter C outside of the bracketis a whole positive number indicating the number of cations linked tothe anion. In the examples given herein C equals c and the sum of n andm equals y-l.

It is to be understood that all compounds of the above named generalstructure have the character of bases (wherein A would be a hydroxylradical) or their salts, including acid salts.

The more important cation-active compounds which may be employed inaccordance with the present invention are the bases or their salts, suchas may be derived from pentavalent nitrogen, and further the sulphonium,phosphonium and arsonium, etc. bases and their salts. The polyvalentatom of X in the foregoing formula is in these compounds nitrogen,sulphur, phosphorus and arsenic, etc., respectively. The quaternaryammonium compounds are examples of compounds containing such an atom,nitrogen being the polyvalent atom. Of these, the pyridonium orpyridinium compounds are examples of compounds in which the polyvalentatom, nitrogen, is contained in a radical, the radical being thepyridine ring (C5H5N) having a valence of two. Other radicals containing'the polyvalent atom may, of course, be used in place of the pyridinerin In the bases or their salts illustrated by the above formula theinnocuous anion symbolized by A is the hydroxide, chloride, sulphate,bromide, iodide, acetate, etc. The groups inducing cation activitysymbolized by Sm comprise extended chain-like structures, such asaliphatic hydrocarbon chains having six or more carbon atoms therein.Also, the extended chain-like structures may be composed of two or morebenzene nuclei or other cyclic radicals, either combined directly. or,for example, through a carbon or nitrogen or other linkages, with orwithout aliphatic chains substituted for the hydrogen in rings.

Referring now in detail to specific examples of suitable compounds,bases derived from nitrogen and their salts, for instance, certainpyridinium and other quaternary ammonium compounds, have been found tobe particularly suitable. The former compounds may include pyridiniumbases or salts having linked thereto extended aliphatic chains,containing, for example, six or more carbon atoms and preferably 12 to20 carbon atoms. Specifically, dodecyl, hexadecyl, octadecyl, or even alower carbon chain such as decyl may be linked to the nitrogen atom inthe bases or salts of pyridinium such aspyridinium hydroxide, pyridiniumsulphate or bisulphalte and pyridinium bromide. Use may also be made ofreplacement or substitute compounds such as the analogous substitutionproducts of pyridine known as picoline (C5H4N(CH3)), and quinoline(CQHIN), etc., and also compounds such as piperidine, acridine,

cinnoline and naphthyridin and their derivatives. 75

' An example of such compound is the bisulphateor acid sulphate ofdodecyl-pyridinium, having the structure:

inducing the surface-activity of the cation may include aromatic orother carbocyclic or heterocyclic radicals. The following compounds areex- In this compound the letter X represents the pyridine radicalincluding the polyvalent atom nitrogen and having a valence y of 2; S isthe dodecyl radical CmHzs connected directly to the polyvalent atom(nitrogen) of X, the letter m being 1. The innocuous anion A is thebisulphate radical (H804) connected directly to the polyvalent'atom ofX. The valence of A is l, and the letter C just outside the bracketis 1. In this compound the value of n is 0, so there would be no atom orradical R.

If the other hydrogen of the bisulphate were replaced by a seconddodecyl pyridinium group the innocuous anion (S04) would have a valenceof 2 and the letter C outside the bracket would become 2, indicating twododecyl pyridinium groups satisfying the two valences of the anion.

In the bases or salts of picoline and quinoline the (C5H4N(CH3)) and the(CQH'IN) groups, respectively, would be the radical X containing thepolyvalent atom, nitrogen.

In the other quaternary ammonium compounds the same innocuous anions andsurface-active groups may be linked to the pentavalent nitrogen atom asare employed with the pyridinium compounds. In this case X representsthe atom nitrogen, having five valences. The three valences which aresaturated in the pyridinium compounds by (CHM are now saturated byalkyl, aryl or other carbocyclic or heterocyclic groups and/or hydrogenatoms. For instance, three' methyl groups may be used to form trimethyldodecyl ammonium bromide. The following is the structural formula ofsuch a compound:

In this case R would be the (CH3) radical, the

letter n being 3, and A would be the bromine atom.

If two butyl radicals are substituted for two of the methyl radicals inthe above compound, methyl-dibutyl-dodecyl ammonium bromide would beformed. In this event the R would represent difierent radicals (CH3 andC4H9) the total number of which would be 3.

Also the compound might contain more than one dodecyl radical or otherradical capable of inducing the surface-activity of the cation. For

letter 11. would, of course, become were.

amples of compounds containing such radicals: including benzene nucleiin the surface-active groups in the cation: toluene azophenyl-trimethylammonium iodide, benzene azophenyl trlj methyl ammonium iodide, diphenylazophen'yl' I i .10 such trimethyl ammonium methyl sulphate, isopropylnaphthyl trimethyl ammonium iodide. In compounds the etc. represent theradicals inducing the surfaceactivity of the cation (S). These may beconnected to a polyvalent atom as in the ammonium salts referred to orto the polyvalent element of a radical, as in the case of the pyridiniumand similar compounds. It is obvious that both aliphatic radicals, forexample, such as the dodecyl group, and carbocyclic or heterocyclicradicals, for example, such as the aromatic azo compounds referred toabove, may be present in the compound as radicals inducing the surfaceactivity of the cation.

Where the innocuous anion is divalent, as in the case of a sulphate inwhich both hydrogens are replaced by surface-active cations, a compoundof the following type may be used:

di (dodecyl-triethyl ammonium) sulphate.

By the same token that the cation-active pyridonium and other ammoniumcompounds are suitable in connection with the present invention,

sulphonium, phosphonium and arsonium bases and their salts may also beused. Of course, in order for this to be true, the sulphur, phosphorusor arsenic must have linked directly thereto, an innocuous anion and atleast one group inducing surface activity in the cation. It is apparentthat the sulphur being tetravalent, as distinguished from thepentavalent phosphorus and arsenic will have less valences to besaturated than in the case of phosphorus, arsenic and nitrogen. Forexample, a sulphonium compound such as dethyl dodecyl sulphoniumhydroxide would correspond to triethyl dodecyl phosphonium hydroxide,either of which might be used. As further examples of these types ofcompounds, trimethyl dodecyl phosphonium hydroxide and dipropyl dodecylsulphonium bromide may be employed.

It is also within the scope of our inventon to use compounds in whichthe polyvalent atom of X is divalent or trivalent. The prerequisites ofsuch an element must be that they will combine with an innocuous anionand a group inducing surface-activity in the cation.

The following are a number of compounds that may be used in accordancewith our invention:

Octyl pyridinium iodide, dodecyl pyridinium bromide, hexadecylpyridinium iodide, octadecyl pyridinium bromide, dodecyl pyridiniumiodide, dodecyl pyridinium chloride, dodecyl-triethyl ammonium iodide,octyl-triethyl ammonium iodide,

decyl-triethyl ammonium iodide, dodecyl-triethyl ammonium iodide,hexadecyl-triethyl ammonium iodide, toluene azophenyltrimethyl ammoniumiodide, benzene azophenyi-trimethyl ammonium iodide, diphenyl-azophenyltrimethyl ammonium methylsulphate, isopropyl naphthyl trimethyl ammoniumiodide, diethyl-dodecyl sulphonium hydroxide, triethyl-dodecylphosphonium hydroxide, trimethyl-dodecyl phosphonium iodide,trimethyl-dodecyl phosphonium bromide, dipropyldodecyl sulphoniumbromide, etc.

Also unsaturated as well as saturated aliphatic radicals may be used asthe radical inducing surface-activity in the cation (S) or as theinactive radical (R).

As pointed out above, the cation-active compounds may be added directlyto the viscose spinning baths, or may be mixed with the viscose solutionprior to extrusion into the baths, or they may be employedsimultaneously in both the bath and spinning solution. It is of coursenecessary to select a cation-active compound which is not adverselyaffected by the acid of the bath and is substantially stable when usedtherein, and/or one that is stable in viscose when used therein.

Compounds which are sufficiently soluble in dilute caustic soda orviscose to go into molecular solution in the viscose itself areparticularly adapted to be added'to the spinning solution.

The tetra-alkylammofiium bases and salts and aryltrialkylammonium basesand salts are especially suited for this purpose because of theirgreater stability toward the alkali of the viscose. When the compound isadded to the spinning bath it is preferred to use a compound that goesinto molecular solution in the spinning bath.

We herewith give three specific examples in order to more clearlydisclose the present process:

Exam 2e 1 9 Ordinary viscose solution is made up, and spun or extrudedthrough fine orifices in precious metal spinnerets into a well-knownacid spinning bath, containing sulphuric acid, sodium sulphate,

ammonium sulphate, and a small quantity of zinc sulphate. Such a bath,although widely known and used, is ordinarily troublesome since spinningdifficulties due to the contaminated spinnerets, are common. We add tothe bath, however, a small quantity (0.04 per cent by weight) of dodecylpyridinium bisulphate. A desirable range of this material is between onethousandth per cent and eight hundredth per cent. Such a small additioneliminates most of the spinning irregularities and difiiculties, andenables a much longer spinning time free from the noted interruptionsthan has been heretofore possible.

Example 2 An ordinary viscose solution is extruded throughgold-palladium spinnerets into a spinning bath of the type mentioned inExample 1, but which contains a relatively larger amount of zincsulphate, for example, five per cent of this salt. Ordinarily, underthese conditions, the spinnerets become sufiiciently contaminated in afew hours to deleteriously affect spinning, as.

pointed out above. However, if 0.1 per cent by weight of dodecyltriethyl ammonium iodideis first added to the viscose solution, thetendency toclog the holes of the spinnerets will be greatly reduced.

. Example 3 An ordinary viscose solution is spun through gold-palladiumspinnerets into a spinning bath containing, for example, in addition tothe usual bath ingredients 5% zinc sulphate: under these conditions theholes of the spinnerets will become contaminated within a few hours. If,however, 0.05% toluene azophenyl-trimethyl ammonium 5 iodide is added tothe viscose solution, there will be much less clogging of the spinneretholes.

We believe it remarkable that such small and relatively inexpensiveamounts of substancesmay be employed, and still give such good results.10

It must be understood that if the addition is made to the spinning bathrather than to the spinning solution, as set forth in Example 1, smallfurther additions are necessary from time to time to replenish thecompound lost or re- 1 moved during the spinning operation.

By "yarn we intend to cover filaments, threads, ribbons, foils, or otherproducts usually produced by extrusion or spinning of a so-calledcellulosic solution of artificial origin. 20

Having now set forth our invention as required by the patent statutes,we desire to be limited only to the extent set forth in the followingclaims.

What we claim is: 25

1. In the manufacture of yarn of artificial origin wherein a cellulosicsolution is extruded through minute orifices into a coagulating mediumto form filaments and the like therefrom, the step which comprisesspinning the filaments 30 in the presence of a dissolved cation-activeammonium compound having linked thereto an atomic grouping containingbenzene nuclei inducing cation-activity and an innocuous anion.

2. A method as defined in claim 1 in which the 86 atomic groupingincludes a chain of benzene nuclei connected by an azo group.

3. In the manufacture of viscose yarn wherein the viscose solution isextruded through minute orifices into an acid precipitating bath to form40 filaments and the like therefrom, the step which comprises spinningthe viscose filaments in the presence of a dissolved, cation-active,aryl substituted ammonium compound having an innocuous anion, saidcompound being substantially 45 stable under spinning conditions.

4. A method as defined in claim 3 in which toluene azophenyl-trimethylammonium iodide is added to the viscose solution before extruding.

5. A method as defined in claim 3 in which 50 about .05% tolueneazophenyl-trimethyl ammonium iodide is added to the viscose solutionbefore extruding.

. 6. A method as defined in claim 3 in whichisopropyl-naphthyl-trimethyl-ammonium iodide 56 is added to the viscosesolution before extruding.

7. A method as defined in claim 3 in which benzeneazophenyl-trimethyl-ammonium iodide -"is added to the viscose solutionbefore extruding.

8. In the manufacture of cellulosic materials 60 of artificial originwherein a viscose solution is extruded through minute orifices into anacid precipitating bath to form filaments and the like therefrom, thestep comprising spinning the filaments in the presence of a dissolvedammonium substituted cation-active compound containing an alkyl groupand an aryl group and an innocuous anion.

9. In the manufacture of cellulosic materials 70 wherein a viscosesolution is extruded through minute orifices into an acid precipitatingbath to form filaments and the like therefrom, the step which comprisesextruding a viscose solution having dissolved therein an ammoniumsubsti- 75 tilted cation-active compound containing an aryl group and aninnocuous anion.

10. In the manufacture of cellulosic materials wherein a viscosesolution is extruded through 5 minute orifices into an acidprecipitating bath to form filaments and the like therefrom, the stepwhich comprises extruding a viscose solution having dissolved therein anammonium substituted cation-active compound containing an aryl group andan alkyl group and an innocuous anion.

JAMES J. POLAK. JOHANNES G. WEELDENBURG.

